Field of Invention
This invention relates generally to an undercarriage of an endless track work machine and more particularly to an undercarriage having a multiple degrees of motion freedom to distribute the weight of the machine and improve vehicle ride quality.
Description of Related Art
A typical tracked work machine utilizes a propulsion system in which a continuous flexible belt is frictionally driven as it is entrained about a main drive wheel and at least one idler wheel. The work machines are configured to maintain adequate tension on the endless belt around the entrained wheels, and to keep the belt in lateral alignment with the wheels when the wheels are subject to large lateral loads. Tracked work machines utilize multiple mid-rollers to distribute the vehicle's weight within the track and to help constrain the track from sliding off the wheels laterally. The main drive wheel drives the endless track belt which propels the vehicle.
Various suspension systems for tracked work vehicles have been developed. Track rollers help distribute the load of the vehicle on the track. In a rigid suspension system, the track rollers are directly mounted to the track frame and loads imparted to the track rollers are directly transferred to the track frame. In an active suspension system, the track frame is provided with a means for dampening the loads imparted to the track rollers which more evenly distributes the load as the tracks encounter obstacles.
In track systems that utilize a tensioning system on the front idler wheel, high reverse drive wheel torque from braking events can cause the track tensioner to retract, resulting in slack in the belt. On positive drive rubber track systems, excessive slack can cause the track drive lugs to disengage from the drive sprocket, causing the track to freely skip over the drive wheel and resulting in degraded braking performance. It would be desirably to provide a system that maintains sufficient track tension to keep the track drive lugs in contact with the drive wheel.